Systems are known from the prior art for monitoring deviations in a web being coated, on an off-line coating machine. In these systems, a defect map of the web is created, based on defect detection that has taken place on the fibre-web machine, which is then displayed to the operators of the off-line coating machine. More specifically, the defect map created on the basis of defect detection taking place on the fibre-web machine prior to reeling is synchronized for the coating machine, where is it displayed to the operators. The defect maps can be further transferred to other subsequent process stages. In addition to this, the post-coating quality can be monitored by imaging the coating web and displaying the deviations found as a defect map. On the basis of these two defect maps, the quality of the web arriving at coating can be seen, as can the quality of the web leaving coating. The defect map, which is imaged after coating, is typically shown in the same display as the defect map that has been imaged prior to coating. By showing the defect maps on the same display, the operator can easily see how the original deviations have changed during coating, provided the web does not break during coating. A method and apparatus for monitoring a rapidly moving web, in which event chains are detected from the web by means of real-time image analyses and displayed in essentially real time, are known from PCT publication WO 2007/096475 A 1.
In the apparatuses according to the prior art, the paper machine, re-reeler, and coating machine are independent units, between which information on deviations causing web breaks on the coating machine is transferred poorly. The poor transfer of information between the units considerably hinders the investigation of the cause-effect relationships of the deviations causing web breaks.